physics key words and definitions

any indication that a measuring system gives a false reading when the true value of the measuried quanity is ero, for exsample, the needle on an ammeter failing to return to ero when no current flows.

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evidence

data which have been shown to be valid

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fair test

a fair test is one which only the independant variable has been allowed to affect the dependant variable.

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falling water

water that transfers gravitational potential energy to kinetic energy.

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frequency

the number of waves crests passing a fixed point every second.

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generator

a machine that produces a voltage.

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geothermal energy

energy from hot under ground rocks.

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gravitational potential energy

energy of an object due to its position in a gravitational field. near the earth's surface, change of g.p.e. (in jouls,j) = weight (in newtons,n) times vertical distance moved (in meters,m). weight ( in jouls,j)

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ground heat

geothermal energy that heats buildings directly.

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haard

a haard is something (for exsample, an object, a property of a substance or an activity) that can cause harm.

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hyothesis

a proposal intended to explain certain facts or observations.

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infrared radiation

electromagnetic waves between visible light and microwaves in the electromagnetic spectrum.

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input energy

energy supplied to a machine.

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insulator

material/object that is a poor conductor.

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interval

the quantity between readings, for exsample, a set of 11 readings equally spaced over a distance of 1 m would give an interval of 10 cm.

the highest group in the classification system, for exsample, animals, plants.

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line graph

used when both variables are continuous. the line should normally be a line of best fit, and may be straight or a smooth curve. (exceptionally, in some (mainly biological) investigations, the line may be a 'point-to-point' line).

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longitudinal wave

wave in which the vibrations are parallel to the direction of energy transfer.

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machine

a device in which a force applied at a point produces another force at another point.

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mass

the quantity of matter in an object; a measure of the difficulty of changing the motion of an object (in kilograms, kg).

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maximise

make as big as possible.

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mean

the arthmetical average of a series of numbers.

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machanical wave

vibration that travels through a substance.

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microwave

part of the electromagnetic spectrum.

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minimise

make as small as possible.

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monitor

observations made over a period of time.

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national grid

the network of cables and transformers used to transfer electricity from power stations to consumers (i.e. homes, shops, offices, factories, ect.).

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newton (n)

the unit of force.

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non-renewable

something that cannot be replaced once it is used up.

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normal

straight line through a surface or boundary perpendicular to the surface or boundary

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nuclear fission

the process in which certain nuclei (uranium-235 and plutonium-239) split into two fragments, releasing energy and two or three neutrons as a result.

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opinion

a belief not backed up by facts or evidence.

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optical fibre

thin glass fibre used to send light signals along.

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oscillate

move to and fro about a certain position along a line.

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payback time

time taken for something to produce savings to match how much it cost.

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pitch

the pitch of a sound increases if the frequency of the sound waves increase.

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plain mirror

a flat mirror.

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power

the energy transformed or transferred per second. the unit of power is the watt (w).

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precise

a precise measurement is one in which there is very little spread about the mean value. precision depends only on the extent of random errors - it gives no indication of how close results are to the true value.